THE LARGE HEARTS OF NEWFOUNDLANDERS AND LABRADOREANS (NL): SUDDEN CARDIAC DEATH (SCD) AND SUDDEN UNEXPLAINED DEATH (SUD) IN FORENSIC AUTOPSY FROM 2004-2013

Abstract

Sudden cardiac death (SCD) is an unexpected event where autopsy confirms a cardiac etiology. Sudden unexplained death (SUD) has negative autopsy findings, where malignant arrhythmias remain the likely cause. Both SCD and SUD in young people may be due to the action of underlying mutations in cardiac genes. All unexpected deaths in Newfoundland and Labrador (NL) are referred to the medical examiner (ME): a centralised system with full ascertainment. 1. Create a database containing all autopsy findings from all deaths 2-50yrs (excluding homicide and suicide) referred to the ME in NL between 2004-2013. 2. Classify cases into likely/unlikely SCD/SUD. 3. Compare heart weight (HW) between the SCD/SUD and non-SCD/SUD groups. This is a retrospective population-based study in NL for ME cases 2004-2013 categorized as “natural”, “accident”, or “undetermined”. All cases were reviewed by the research team. Means were compared using student T test and ANOVA. Logistic regression assessed strength of determinants. From 1152 ME cases, 386 SCD/SUD cases were ascertained. The annual incidence rate was 12 per 100,000 person-years (≈ three SCD/SUDs per month), with a male to female ratio of 3:1 (p < 0.0001). The incidence of SCD/SUD gradually increased with age. The incidence of SUD was 2 per 100,000 persons-years, and accounted for most deaths in people ≤ 29yrs (p < 0.0001) while coronary artery disease (CAD) was predominant among people ≥30yrs (p < 0.0001). From 1152 cases, HW was reported in 782. Mean HW was greatest in the SCD group (n=348) and lowest in the non SCD group (n=434) (p< 0.0001). The heaviest hearts in the SCD/SUD and non-SCD/SUD groups were 944gm and 740gm respectively (mean normal HW is 250-350gm). Comparing mean HW between diagnoses in the SCD group (CAD, congenital heart defect, cardiomyopathy, SUD) showed significant differences between groups (p < 0.0001). BMI was not a significant factor in determining heart weight. In ME deaths (2-50yrs) between 2004-2013, high incidence rates of SCD and SUD were reported. SUD's (likely arrhythmogenic deaths) are a significant cause of death in the young, which may reflect underlying cardiac arrhythmia mutations in NL. The SCD group has the highest mean HW, unrelated to BMI. Regardless of the cause of death, mean HW is greater than reported in the literature, and maximum HW across all groups is excessive.